NZ praying mantises fall victim to South African females

New Zealand native praying mantis.

More than two-thirds of native male praying mantises are devoured by South African females - lured to their doom by an irresistible erotic scent.

Research by the University of Auckland found the delicate New Zealand male approaches the exotic female enthusiastically, lacking the in-built caution South African males have when wooing their aggressive potential mates.

In a cruel twist, even though our males find the foreigners more attractive than homegrown females they are unable to mate with them, so die in vain.

Behavioural ecologist Dr Greg Holwell said about 70 per cent of naive male natives are killed and eaten - with the knock-on effect that native females struggle to find a partner.

Dr Holwell said native praying mantises are officially "at risk" and we need to get rid of the overseas interlopers. Putting them in the freezer is the recommended approach, but it's important to know which species is which.

South African praying mantises are larger. The females often have large, swelling bellies and the necks of both males and females are noticeably narrower than their heads.

Natives have necks nearly as thick as their bodies and distinctive blue-purple patches on the inside of their front legs.

The decline of our native species was thought to be linked with competition for food. However, Dr Holwell's research indicates sexual cannibalism is a more likely theory.

The research has attracted international attention and the University of Auckland study led by student Murray Fea, with assistance from Dr Holwell and his colleague Dr Margaret Stanley, has been published in the journal Biology Letters.

Dr Holwell has been studying praying mantises for 12 years.

His research has uncovered a number of new species and behaviours, including the finding that for some species, females have more offspring when they eat their mates.